/Engine/Source/Runtime/Core/Public/Tasks/TaskPrivate.h
The number of times that the task should be unlocked before it can be scheduled or completed initial count is 1 for launching the task (it can't be scheduled before it's launched) reaches 0 the task is scheduled for execution. NumLocks's the most significant bit (see `ExecutionFlag_) is set on task execution start, and indicates that now NumLocks is about how many times the task must be unlocked to be completed
static constexpr uint32 NumInitialLocks = 1;